Lead-in conductor for electron discharge devices



Jan. 2, 1951 2,536,636

LEAD-IN CONDUCTOR FOR ELECTRON DISCHARGE DEVICES O. H. FULTON, JR

Filed Nov. 15, 1946 (Ittomeg Patented Jar 1 2, 1951 UNITED STATES PATENTOFFICE LEAD-IN CONDUCTOR FOR ELECTRON DISCHARGE DEVICES Oliver H.Fulton, J12, Montclair, N. J., assignor to Radio Corporation of America,a corporation oi Delaware 10 Claims.

The present invention relates to lead-in com doctors for electrondischarge devices and more particularly to lead-in conductors of thetype having a relatively rigid portion for sealing through an envelopewall of the device and relatively flexible portion for connection to ane1ectrode within the device.

In devices of the type useful at high frequencies the lead from theinput, or control grid elec trode, is frequently taken from the end ofthe device remote from the base and the lead from the output, or anodeelectrode, extending from the base of the device, so as to secure themaximum spacing between these leads to avoid undesirable capacityeffects therebetween.

The lead taken from the end of the device remote from its base includesin some cases a rigid metallic rod portion adapted to form aglass-to-metal seal with the envelope wall of the device. The lead-inalso includes a portion which is more flexible than the rod portion andwhich is designed for connection to an electrode of the device, forexample, the control grid.

In practice, as heretofore followed, the electrode mount of the deviceis usually first prepared and includes the lead-in conductor for use atthe end of the device remote from the base. The resilient portion of thelead-in is usually fastened as by welding to one of the electrodes, andthe rod portion thereof is disposed coaxiall with respect to the mount.The envelope blank is provided with an aperture at its' end remote fromthe base, through which the rod portion of the lead-in is extended whenthe mount is fixed in position within the envelope prior to scaling thelead in the wall of the envelope.

Several problems are associated with this practice. One of theseproblems concerns the need for maintaining the rod portion of thelead-in in coaxial relation to the mount when it is threaded into theenvelope aperture referred to. The means for maintaining the rod portionor" the'lead-in' in this relation is also required to be sufii'cientlyflexible so that any stresses applied to the lead-in laterally can beabsorbed by such means and not transmitted to the electrode servedthereby. Such stresses might easily occur on insertion of the mount inthe envelope due to improper line-up of the envelope and mount,

and thermal expansion of the parts involved.

In addition, there are problems created by the inherent structure oflead-in of the types discussed. For instance, the provision of aflexible portion of the lead-in has involved a reduction in thecross-section area of this portion to such extent that it possesses verylittle heat conducting ability. Furthermore, the usual practice offorming this flexible portion of the lead-in in the shape of a pig tailto increase its flexibility, results in undesirable inductance effectsat high frequencies and extends the length of the path of high frequencycurrents to the electrode served by the lead-in.

It is an object of my invention to provide an improved lead-inconstruction for an electron discharge device particularly suitable foruse at high frequencies.

It is another object to provide a lead-in for an electron dischargedevice which is substantially free from the objections enumerated in theproblems referred to.

It is a further object to reconcile the mutually opposed structuralconsiderations of a lead-in for an electron discharge device to providea device in which the lead-in contributes to convenience of assembly andgood operation of the device.

Another object is to provide a lead-in for an electron discharge devicewhich possesses desired physical characteristics for contributingfacility to assembly, assurance of maintenance of desired spacings, andgood heat conductivity as well as desired electrical characteristics ofshort paths for high frequency currents and reduction of inductiveeffects therein.

An additional object is to provide a method of making a lead-in for anelectron discharge device having the advantages referred to in thepreceding object.

These objects, as well as others which will suggest themselves as thisdescription proceeds, are attained according to my invention by a novelstructure, and method of making, a lead-in conductor.

While the invention itself is pointed out with parti ularity in theappended claims, it will be best understood from a detailed descriptionof an embodiment thereof presented solely for illustrative purposes,taken in connection with the appended drawing. In the drawing to whichrefence is now made,

Figure 1 is an elevation of an electron discharge device with parts cutaway to more clearly depict novel lead-in conductor;

Figure 2 is a transverse section along line 22 of Figure l and shows themanner in which the flexible portion of the conductor is connected tothe rigid portion thereof, and the ease with which the arms of theflexible portion may be connected to the projecting portions of the twoside rods of a grid;

Figure 3 shows a plan view, partly in section, of'a step in my method ofmanufacture wherein the rigid portion of my conductor is attached to theflexible portion thereof in transverse and substantiall line engagementtherewith;

Figure 4 shows another step in my novel method wherein the rigid portionof the conductor has been given a twist coaxially in a clockwisedirection; and

Figure 5 shows a side view of my completed lead-in conductor.

Referring now to the drawing in more detail, there is shown in Figurel apentode of the miniature tube type having a glass envelope is includinga glass base i! enclosing an electrode mount including electrodescomprising an anode I2, suppressor grid i3, i3a, shielding grid i l,control grid l5 and cathode it, supported on insulating spacer platesll, iii. The electrodes are connected to suitable leads one of whichincludes lead is passing through the envelope of the end thereof remotefrom the base, and the other of which includes base contact pins 29passing through base ii. Lead it serves the input or control gridelectrode i5 and the leads 2B serve the other electrodes including theanode 12 or output electrode of the pentode. This arrangement results ina maximum spacing of the leads to the input and output electrodes forreduction of undesired electrical effects therebetween.

According to the invention, lead 49 is con structed of two partscomprising the comparatively rigid metallic rod l9 and the relativelyflexible metallic ribbon 2!. The ribbon 2i embraces an end portion ofthe rod iii in a fixed and part frictional engagement at sub stantiallya longitudinally middle portion of the ribbon to provide two arms. Thewider surfaces of ribbon 2i lie in planes parallel to the longi--tudinal axis of rod [9. The ends 22, 23 of the arms of ribbon 2i arebent in parallel relationship to rod IS without disturbing the parallelrelationships of the wider surfaces thereof to the longitudinal axis ofrod i9 and are suitably connected to side rods [5 of the control gridwhich are spaced apart from each other. The rod is is sealed through theenvelope at the end thereof remote from the base H. Although the crosssectional form of ribbon 2! is relatively narrow, this form issufficiently long to provide a cross sectional area substantially equalto that of the rod l9.

Figure 2 shows more clearly the engagement between ribbon 2i and rod [9.Ribbon 2i is fixedly connected to rod is at portion 24, as by welding,which is substantially linear across the ribbon and parallel to the rod.The fixed connection between rod is and ribbon 2!, therefore, includesrelatively small surfaces of these memhere. The remainder and largerportion of surface engagement between rod is and ribbon 2! is not fixedother than by friction between the members and the elasticity of theribbon.

These structural characteristics of my novel lead-in contributeadvantages both during assembly and subsequent operation of an electrondischarge device in which they are incorporated.

Thus, during assembly of the device and particularly during the step ofextending one of the lead-ins through the aperture in the enveloperemote from its base, it is necessary to take care that no strains areplaced on the mount or on any electrode thereof. Such strains may resultfrom failure of the lead-in to properly register with the envelopeaperture and the use of force to accomplish such registeringrelationship. This failure to register may be occasioned by faultyline-up which requires a lateral displacement of the lead-in as a remedytherefor. The structure of my novel lead-in permits easy lateraldisplacement thereof with respect to the mount so that the desiredline-up of the leadin and the mount may be effected Without harmfulstrains on the electrode connected to the lead-in. As will be apparentfrom Figure 2, lateral strains between rod is and grid !5 can easily beabsorbed by the ribbon 2! since it is out of alignment with thedirection of such strains and receives them normal to its widersurfaces.

An additional feature of my novel lead-in which facilitates assembly ofthe device in which it is employed a desired rigidity of the leadinstructure axially of the electrode mount. This rigidity is desirable forconvenience in extending a portion of the lead-in through the envelopeaperture referred to. However, while the structure is sufficiently rigidto prevent axial contraction of the lead-in during normal conditions ofassembly, it possesses sufiicient flexibility axially to prevent damageto the mount in the event unusual strains should be encountered. Thisaxial flexib'lity of my lead-in structure wh iicient to disturb thedesired a. a1 1' ty rere ed to, results from the novel manner joining throd is thereof to the ribbJn 25 in a only a portion of which representsa fixed connec ion between these members of the lead-in.

In addition to proving advantageous in the assembly of an electrondischarge device, my novel lead-in also contributes to good operation ofthe device. Thus any lateral strains on the lead-=in within the envelopeduring operation of the evice arising, for example, as the result ofthermal conditions, will be absorbed by ribbon 2i and will not betransmitted to the electrode connect;d thereto. Also if the grid siderods expand due to heat the lead will flex and not distort the grid. inaddition, the fact that the cross-sectional area of the ribbon 2i issubstantially equal to that of the rod it results in heat conductingqualities of the lead-in which are unimpaired by the flexible characterof the ribbon 2E. Moreover, the provision of two arms 22, 23 on theribbon 2% permits connection of the leadin to two spaced portions of anelectrode to further contribute to heat dissipation from the electrode.The relatively large surface engagement between the ribbon 2i and rod Itfurther aids in heat oonduc tion from the electrode associated with thelead-1n. Furthzrmore, since no portion of the lead-in is coiled, thegeneration of undesired inductance effects is prevented and a shorteningof the electrical path through the lead-in is effected.

Figures 3, 4 and 5 show steps in my novel method of making the lead-inof my invention. In Figure 3 ribbon 24 is shown fastened as by weldingat 2 3 to rod it. Ribbon 2! is then held against torsional movement asby chucks 25, 26, while rod I9 is given an axial twist in the directionof the arrow. A transverse portion of the rod I9 is then engaged in afold by ribbon 2|, the fold engagement being faci'itated by the fixedconnection 25, which is substantiahy linear axially of rod is. Theresultant structure is shown in Figure 4. Thereafter, the ends 22, 23 ofthe arms of ribbon 2| are folded as shown in Figure 5 8 so that they areparallel to rod l9 and have a side edge facing this rod. The lead-in maythen be connected to spaced portions of an electrode, such as thecontrol grid side rods l as shown in Figure 1 to complete the electrodemount for placement within an envelope.

While an embodiment of my invention has been described, my invention isnot to be regarded as limited to the particular features thereof. Thisembodiment may be subjected to many modifications by persons skilled inthe art without departing from the invention as pointed out in theappended claims.

I claim:

1. A lead-in conductor for an electron discharge device comprising aflexible portion and a rigid portion, said rigid portion comprising ametallic rod, said flexible portion comprising a metallic band, saidband being fixedly connected to said rod adjacent one end thereof insubstantially a straight line contact transversely of said band, andfrictionally and resiliently connected thereto by surface contact, saidflexible portion including oppositely extending arms having end portionsparallel to said rod for connection to spacedapart portions of anelectrode.

2. Lead-in conductor for an electron discharge device including a rodfor sealing through the glass wall of said device and a metallic bandfor connection to spaced apart portions of an electrode, said band beingfrictionally connected to said rod by embracing a transverse portion ofsaid rod in a fold, and fixedly connected to said rod at a portion ofsaid fold, said fold being transversely of said band, said band havingend portions bent at right angles with respect to said band and lying inplanes parallel to said band.

3. A lead-in for an electron discharge device comprising a conductingrod to be sealed through the envelope of said device, and a flexibleribbon conductor mounted transversely of the rod at one end thereof,said ribbon conductor having its wider surfaces lying parallel to saidrod and having a loop intermediate its ends encompassing and contactingsaid rod, said ribbon being fixed to said rod along a linelongitudinally of said rod, the ends of said ribbon being folded over tobe parallel to said rod and to engage spaced portions of an electrode ofsaid device.

4. A lead-in for an electron discharge device comprising a conductingrod and a flexible ribbon conductor having a portion intermediate itsends wrapped transversely around an end portion of said rod for engagingmore than 180 degrees but less than the whole of the periphery of saidrod, said ribbon conductor having end portions extending from differentsides of said rod.

5. A lead-in for an electron discharge device comprising a conductingrod and a flexible ribbon, said ribbon having an intermediate portionwrapped around an end portion of said rod and engaging more than 180degrees of the periphery of said rod, whereby the two end portions ofsaid ribbon extend laterally from said rod, one of said two end portionsbeing folded upon itself for extending from a different side of said rodthan the other of said two end portions, whereby said two end portionsare adapted to be connected to displaced portions of an electrode withinsaid device.

6. A lead-in for an electron discharge device comprising a rigid rod anda flexible ribbon, said ribbon at an intermediate portion thereof beingwound transversely of an end portion of said rod to engage more thanhalf the periphery of said rod, whereby the two end portions of saidribbon extend laterally from said rod, one of said two end portionsbeing bent to provide a fold upon itself adjacent said rod for extendingfrom said rod in a different direction from the other of said two endportions, said ribbon being fixed to said rod adjacent said fold,whereby said lead-in is responsive to forces normal to said rod foraccommodating said lead-in to an electrode variably spaced laterallywith respect to said rod.

7. A lead-in for an electron discharge device comprising a rigid rodfixed to the envelope of said device in a seal and a flexible ribbonfixed to said rod and to spaced portions of an electrode, said ribbonincluding two arms extending from different sides of said rod, each ofsaid arms includin a plurality of folds between said rod and saidelectrode for permitting displacement of said electrode from said rodwithout impairing said seal and the structure of said electrode.

8. An electron discharge device including a grid having two spaced siderods, and a lead-in for said grid connected to said side rods, saidleadin comprising a rigid rod fixed to the envelope of said device in aseal, and a flexible ribbon mounted intermediate its ends on said rod,the ends of said ribbon being fixed to said side rods, and two folds insaid ribbon intermediate said rod and each of said side rods forabsorbing forces resulting from misalignment of said grid with respectto said rod without impairin said seal and said grid.

9. A lead-in for an electron discharge device comprising a rigidconductor for sealing through the envelope of said device, and aflexible ribbon fixed intermediate its ends to said rod, the ends ofsaid ribbon being adapted to be connected to spaced portions of anelectrode within said device, said ribbon being folded along twoangularly disposed lines between said rod and each of said spacedportions for providing a flexible connection between said rod and saidelectrode.

10. A lead-in for an electron discharge device comprising a, rigidconductor for sealin through the envelope of said device, and a flexibleribbon fixed to said rod and to an electrode within said device, saidribbon having plurality of folds therein for providing a resilientconnection between said rigid conductor and said electrode.

OLIVER H. FULTON, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

